Jupiter is the king of the planets. It is the biggest planet in our solar system, a giant ball of gas with no solid surface to stand on. For hundreds of years, astronomers have known Jupiter by its most famous feature: the Great Red Spot. This giant, swirling storm is so big that it makes Earth’s hurricanes look like tiny pinwheels. It is a famous landmark, like a giant eye staring out into space.
For centuries, this storm seemed permanent. It was always there, spinning and churning in Jupiter’s southern half. But in recent decades, scientists have noticed something dramatic. The Great Red Spot is changing. Telescopes and space probes have confirmed that the storm is shrinking, and it seems to be shrinking faster than anyone expected. This discovery has led to headlines around the world, all asking the same big question.
We see pictures of it getting smaller, and we hear reports that it is becoming less of an oval and more of a circle. This has everyone worried that this iconic feature might one day be gone for good. Is the solar system’s greatest storm finally running out of steam?
What Exactly Is the Great Red Spot?
The Great Red Spot is not land. It is not a mountain or a crater. It is a gigantic storm, and a very special kind of storm at that. Scientists call it an anticyclone. This just means it is a high-pressure system. On Earth, high-pressure systems usually bring clear skies and calm weather. But on a gas giant like Jupiter, a high-pressure system creates a massive, spinning vortex that can last for an incredibly long time. Because the storm is in Jupiter’s southern hemisphere, it spins counter-clockwise.
The size of this storm is difficult to comprehend. In the late 1800s, when astronomers first measured it accurately, the Great Red Spot was enormous. It was about 25,000 miles (over 40,000 kilometers) wide. To put that in perspective, you could have lined up three entire Earths side by side inside the storm. But it is not that big anymore. Today, its width is closer to 10,000 miles (about 16,000 kilometers). It is still huge, easily wide enough to swallow our entire planet, but it is a shadow of its former self. Its age is just as impressive. We have solid, continuous records of it existing since at least 1878. However, some earlier telescope drawings from the 1600s show a large spot on Jupiter, leading many scientists to believe the storm could be at least 350 years old.
How Do We Know the Great Red Spot Is Shrinking?
We know the storm is shrinking thanks to a long history of careful observation. It started with astronomers drawing what they saw through early telescopes in the 1800s. These drawings clearly show a long, oval-shaped storm. But our best information comes from the modern space age. In 1979, NASA’s Voyager 1 and Voyager 2 spacecraft flew by Jupiter. They gave us our first stunning, close-up photographs, which confirmed the storm’s size and swirling nature. The Voyager images provided a clear benchmark, showing a storm that was still about 14,500 miles wide.
Since 1990, the Hubble Space Telescope has been our most consistent watchdog. Hubble has been taking regular pictures of Jupiter for decades as part of a program called the Outer Planet Atmospheres Legacy (OPAL). This long-term monitoring has created a time-lapse video, showing without a doubt that the storm is getting smaller every year. The images clearly show its long oval shape shrinking into a more circular one. And since 2016, NASA’s Juno spacecraft has been orbiting Jupiter, flying closer to the storm than any probe in history. Juno’s instruments are not just taking pictures; they are measuring the storm’s depth and structure, giving us the most detailed data we have ever had. All this combined data, from 19th-century drawings to 21st-century probes, tells one clear story: the Great Red Spot is shrinking.
Why Is the Great Red Spot Changing Shape and Size?
This is the big mystery that scientists are working hard to solve, and they do not have one simple answer. Jupiter’s atmosphere is an extremely complex place, and the storm is a very complex system. However, scientists have several strong theories about what is happening. One idea is that the storm is simply running out of energy. Think of it like a spinning top. When you first spin it, it is fast and stable. But over time, friction makes it slow down, wobble, and eventually stop. The Great Red Spot has been spinning for centuries, and it might just be reaching the end of its life.
Another popular theory involves something called “flaking.” Scientists observing the storm have seen smaller storms and weather patterns on Jupiter interact with the Great Red Spot. These smaller vortices sometimes get close to the big storm and seem to “chip away” at its edges. These events, nicknamed “flaking,” look like blades of red gas are being pulled off the main storm. If this happens often enough, it could be “eroding” the storm and making it smaller over time. It is also possible that the jet streams, the fast-moving bands of wind that circle Jupiter, are changing. These jet streams border the storm to its north and south. If their path or speed has changed, they might be “squeezing” the storm, forcing it into a smaller, more circular shape. Some studies suggest that as the storm shrinks in width, it is actually getting taller (or deeper), like a ball of clay being squeezed. This might be a sign that it is not dying, but just changing its shape as its energy compacts.
What Gives the Great Red Spot Its Red Color?
You might be surprised to learn that nobody knows for sure what makes the storm red. This is one of the most persistent mysteries in planetary science. Jupiter’s upper clouds are mostly white or yellowish, made of frozen ammonia crystals. The red color must come from some other chemical. The most popular theory is that the powerful storm dredges up material from deep within Jupiter’s atmosphere. These chemicals, which might include compounds of sulfur or phosphorus, are pulled up many miles high, far above the main cloud decks.
Once these chemicals are exposed to the harsh ultraviolet (UV) radiation from the Sun, a chemical reaction occurs. This process, called photochemistry, is believed to split the molecules apart and reform them into new, more complex compounds. These new compounds, sometimes called “chromophores” (which means “color-bearing”), are a bit like soot or rust and are very good at absorbing blue and green light, which makes them appear reddish or brownish to our eyes. This theory would also explain why the color of the storm changes. Sometimes it is a deep brick red, and other times it fades to a pale salmon or orange. This might mean the storm is not always pulling up the same amount of this “mystery material,” or that the strength of the storm is changing, affecting how high the material gets.
How Powerful Is This Storm Compared to Storms on Earth?
Comparing the Great Red Spot to an Earthly hurricane is like comparing a bonfire to a star. Both are in the same category, but the scale is just not comparable. The most powerful hurricanes on Earth, Category 5 storms, have wind speeds that start at around 157 miles per hour (252 kilometers per hour). These storms are terrifying and can cause massive destruction. Now, let’s look at Jupiter. The winds around the edge of the Great Red Spot have been measured at over 270 miles per hour (434 kilometers per hour). And some models suggest winds deeper inside could be even faster. Interestingly, the very center of the storm is thought to be relatively calm, much like the “eye” of a hurricane, but on a planetary scale.
Then there is the size. A large hurricane on Earth might be 500 miles wide. As we discussed, the Great Red Spot is currently 10,000 miles wide. It is wider than our entire planet. But the biggest difference is duration. An Earth hurricane gets its energy from warm ocean water. Once it moves over land or cool water, it loses its fuel source and dies out in a matter of days or, at most, a few weeks. The Great Red Spot has been raging for at least 150 years. This is because it is not powered by water. It is powered by Jupiter’s own internal heat. Jupiter is so massive that it is still cooling down from its formation 4.5 billion years ago. It actually gives off more heat than it receives from the Sun. This internal heat constantly churns the atmosphere and acts as a massive engine for the storm, which is one reason it has lasted so long.
What Has the Juno Mission Taught Us About the Storm?
NASA’s Juno spacecraft, which has been orbiting Jupiter since 2016, has completely changed our understanding of the Great Red Spot. Before Juno, we could only look at the storm’s cloud tops. We had no idea what was happening underneath. But Juno has an instrument called a Microwave Radiometer (MWR) that can peer deep beneath the clouds, sensing the temperature and structure of the atmosphere hundreds of miles down. When Juno flies over the Great Red Spot, it uses this instrument to “X-ray” the storm.
The single most important discovery Juno has made about the storm is that it is not a shallow weather feature. It is incredibly deep. Juno’s data shows that the storm’s “roots” extend at least 300 miles (500 kilometers) down into Jupiter’s atmosphere. For comparison, the deepest part of Earth’s ocean is only about 7 miles deep, and Earth’s entire atmosphere (the part with weather) is only about 10 miles thick. The Great Red Spot is a three-dimensional monster, far deeper than anyone had predicted. This deep structure helps explain why it has been so stable and long-lived. It is not just floating on the surface; it is anchored deep within the planet’s churning interior, plugged into the massive heat engine of the planet. Juno’s measurements of the storm’s gravity field have also helped scientists weigh the storm, confirming it contains a huge amount of mass.
So, Will the Great Red Spot Actually Disappear Soon?
This is the billion-dollar question. The answer depends on what you mean by “soon.” Based on the data from Hubble and other telescopes, the rate of shrinking is undeniable. If you simply draw a straight line on a graph, some calculations have suggested the storm could become a small circle and then vanish entirely within the next 20 to 50 years. This is the “dying” hypothesis, which suggests the “flaking” events are tearing it apart faster than it can sustain itself. This would be incredibly soon in astronomical terms.
However, many scientists are not convinced it will be that quick. The discovery by Juno that the storm is so deep suggests it is more resilient than we thought. The “squeezing” hypothesis suggests the storm is not dying, but changing. It is losing its wide oval shape and becoming a more compact, circular, and deeper storm. It might be rearranging itself to become more stable in Jupiter’s current atmospheric conditions. In this view, the shrinking might slow down, and the storm could persist in its new circular form for many more decades, or even centuries. So, while it is very unlikely to vanish in the next few years, its long-term future is uncertain. We are in the unique position of watching a giant, ancient feature of our solar system evolve and possibly fade away right before our eyes.
What Would Jupiter Look Like Without the Great Red Spot?
It is a strange thought for astronomers and space lovers. For the entire history of modern astronomy, Jupiter has had its spot. Seeing the planet without it would feel like seeing a familiar face that has suddenly changed. The planet’s “face” would look much emptier in its southern hemisphere, dominated only by the parallel bands of its belts and zones. But this does not mean Jupiter’s weather would stop. The planet would still be a chaotic and dynamic world, covered in thousands of other storms.
In fact, Jupiter has other, smaller “red spots.” The most famous is called “Oval BA,” or sometimes “Red Spot Jr.” This storm formed in the late 1990s when three smaller white storms collided and merged. Then, around 2005, this new storm turned the same reddish color as the Great Red Spot. This is a crucial clue. It shows that the chemical and physical processes that create large red storms are still active on Jupiter. So, even if the Great Red Spot does disappear, it is very possible that in a few hundred years, a new “Great Spot” could form somewhere else on the planet. Jupiter’s atmosphere is a storm factory, and the Great Red Spot is just its most famous creation.
Why Is Studying This Storm So Important for Science?
Studying the Great Red Spot is not just about watching a storm. It is a unique natural laboratory for understanding how weather works under extreme conditions. On Earth, our weather is complicated by oceans and land. On Jupiter, it is a pure atmospheric system, driven by rotation and internal heat. By studying the GRS, scientists can test and improve their computer models of “fluid dynamics,” the science of how gases and liquids move. These same principles apply to everything from ocean currents on Earth to the atmospheres of other planets.
Speaking of other planets, in the last few decades, we have discovered thousands of planets orbiting other stars. Many of these “exoplanets” are gas giants, just like Jupiter. How do their atmospheres work? Do they have storms? Do they have their own Great Red Spots? By understanding the physics of our GRS, we can make much better predictions about what these distant worlds are like. Finally, the storm’s chemistry tells us about Jupiter’s interior. The materials dredged up to create the red color are a sample from deep inside, giving us clues about the planet’s composition. This, in turn, helps us understand how Jupiter, and our entire solar system, first formed 4.5 billion years ago.
Conclusion
The Great Red Spot is, without a doubt, shrinking. We have watched it go from a giant oval that could swallow three Earths to a smaller circle that can barely hold one. Missions like Juno have shown us that it is not just a surface feature but a storm of unimaginable depth, rooted hundreds of miles into the planet.
Scientists are still debating whether it is in its final “dying” phase or just “evolving” into a new, more stable shape. It probably will not disappear tomorrow, or even in the next ten years. But it seems clear that its centuries-long reign as the unchanging king of storms is coming to an end. We are lucky to live at a time when we can watch this grand celestial giant change.
As we watch this ancient storm fade, it makes you wonder: what other amazing, long-lived phenomena are happening right now on other planets, just waiting for us to discover them?
FAQs – People Also Ask
How old is the Great Red Spot?
Scientists know for sure that the Great Red Spot has been continuously observed since at least 1878, making it over 145 years old. However, some earlier drawings and notes from astronomers as far back as the 1600s might show the same storm, which could make it over 350 years old.
Can you see the Great Red Spot with a telescope?
Yes, you can see the Great Red Spot from Earth, but you need a good-quality backyard telescope, not just binoculars. It appears as a faint, pale oval against Jupiter’s brighter cloud bands. The best time to see it is when Jupiter is close to Earth and the spot is rotating into view.
What is the Great Red Spot made of?
The Great Red Spot is made of gases, primarily hydrogen and helium, which make up most of Jupiter. Its distinct color likely comes from trace amounts of other chemicals (like ammonia compounds) that are pulled up from deep inside the planet and then zapped by sunlight, which turns them reddish.
Is the Great Red Spot getting taller as it shrinks?
Some scientific models and observations suggest that yes, as the storm’s width has gotten smaller, its “height” or depth has actually increased. Imagine squeezing a ball of clay on its sides; it gets thinner but also taller. The storm may be compacting its energy.
What is a “flaking” event on Jupiter?
A “flaking” event is a name astronomers use for when smaller storms or sections of jet streams get close to the Great Red Spot. These encounters can look like they are “chipping” or “peeling” off red-colored gas from the edge of the main storm, which might be contributing to its shrinking.
Is Jupiter’s “Red Spot Jr.” also shrinking?
Red Spot Jr., officially named Oval BA, is a smaller storm that turned red in the mid-2000s. Its behavior is more variable than the Great Red Spot. It has been seen to change color, size, and intensity, sometimes fading and sometimes strengthening, but it does not show the same steady, long-term shrinking as the GRS.
How fast are the winds inside the Great Red Spot?
The winds around the outer edge of the Great Red Spot are incredibly fast, consistently measured at over 270 miles per hour (434 kilometers per hour). This is much faster than the strongest Category 5 hurricanes on Earth. The very center of the storm is thought to be much calmer.
Why is the Great Red Spot red?
Scientists are not one hundred percent sure, but the leading theory is that the storm’s powerful updrafts pull chemicals from deep inside Jupiter up to the top of the atmosphere. When these chemicals are exposed to strong ultraviolet (UV) light from the Sun, they undergo chemical reactions that create complex, “reddish” colored compounds.
What mission is studying Jupiter right now?
The primary mission studying Jupiter right now is NASA’s Juno spacecraft, which has been in orbit since 2016. Juno’s main goal is to understand Jupiter’s origins, interior structure, deep atmosphere, and powerful magnetic field. It makes close flybys over the planet’s poles and the Great Red Spot.
How big is Jupiter compared to Earth?
Jupiter is enormous. It is so big that you could fit 1,300 planets the size of Earth inside of it. Its mass is more than two and a half times that of all the other planets in our solar system combined.